The universe is not a line [one dimension], the universe is a volume in a time. This means that the expanding space-time has got no edges. I could ask you: where does the surface of the Earth end? If you begin to travel West you will be able to travel for all your life without meeting an "end". About the universe it seems to be almost the same. We travel on the surface of a multi-dimensional entity and we will never meet an "end".
I would say the surface of the earth ends right on the top layer of the surface of the earth. By comparing the universe to earth are you saying you believe the universe is a globe? You say expanding universe. What is the universe expanding into? What is intitally there before the universe expands into in?
Imagine a concentration of all mater and energy concentrated to a single point then exploding in a vacuum with nothing to really prevent the travel of matter end energy with no end in sight. This is the universe at day zero. We know the speed is decreasing, meaning there is some force interacting, sometime called dark matter. The universe is a logical chaos.
How do you know it was day zero? Perhaps it's a cycle. Expansion eventually grinds to a halt, everything is slowly attracted back together, big boom. Repeat. I find all this fascinating but my mind fails to cope. How was all matter even created in the first place? If energy can't be created it destroyed , how did it even come to be? I do think the creation of matter would be day zero, but could it even be created? Also still can't get my head around infinite vacuum. How?
The example of the Earth [or of a balloon] works if you imagine that our space-time is the surface of the balloon. It keeps on expanding towards nothing and there are no limits or borders in itself. If you want to enter the balloon [or Earth, in my comparison] you need to travel through other dimensions. I can explain this with the example of a 2D world. On a curved sheet of paper draw two houses. A 2D being to pass from a house to an other will have to walk [in 2D, a bit like ancient Egyptians!]. But what f he adds a dimension, traveling through the "vacuum"? From the perspective of other 2D beings he will disappear from house A to appear in house B. The universe seems to be very similar: a curved 3D [or 4D, depending on how you consider time ... usually in quantum physics it's not a dimension, while in relativity you talk about space-time] "surface". But curved in which? In further dimensions ...
The conceptions of "before" and "eternal" don't make great sense about the beginning of the universe, since time came to existence with the universe. There is no "before" ...
Regarding the Universe(s), I suggest we cannot, or will never, know enough to make any hard predictions.
Good questions. As I see it (correct me if there are problems with this): At present, measurement appears to indicate that our universe is actually expanding at an increasingly fast pace. Of couse that would mean it won't collapse back again - at least as long as there isn't some other factor yet to be discovered - which isn't impossible.. The "big bang" theory doesn't address the issue of how the initial blob came into being. It only takes over in describing how the expansion of that blob worked. To figure out what was the state at time=0 (or "before") one would probably have to think about what is going on outside our universe - and, it's really hard to get evidence of that. The term "Infinite vacuum" that you use sounds to me like the model where the universe explodes into a vacuum that is huge, possibly infinite. But, that model is NOT what physicists believe is happening (or happened). They point out that our usual concept of a vacuum is something that is truelly empty. But, physicists find that vacuums have "vacuum energy". Scientists can wantch matter come into existence and then go out of existence in a vacuum. Einstein points out that energy and matter are equivalent, so with vacuums having energy it isn't surprising that the form of that energy could move between matter and not matter. So, the vacuum of space has to be PART of the big bang just like everything else. There isn't a preexisting vacuum. And, the big bang is the expansion of the initial starting blob - NOT an explosion into a vacuum. The result of that is our universe - an expanding blob of energy and particles that includes absolutley everything - vacuum of space, energy, particles, light, whatever, all interacting according to laws of physics that have brought about stars, Earth, etc. Today, the rate of expansion can be measured by astrophysicists by looking across huge distances. My toe is also expanding, but by too little to measure directly. Besides, our measrement tools are expanding at the same rate since they are part of our univerese.
Good point but mathematics really isn't nature. It is a man made tool for science. There is an infinity symbol in mathematics as well. Whenever it is used we know there is something wrong with the mathematics. I liked the post nevertheless.
For there to be an end point that implies that there was a beginning point. There is no scientific evidence for either a beginning or an end of the universe. Space-time has always existed. We are merely observing space-time from our own limited perspective. We do not have the tools capable of observing the limits of the universe if they even exist. There is a growing body of scientific thought that embraces the concept of a cyclical universe. Nothing is unique in the universe because as soon as we discover something new we soon discover others of the same type. If this principle holds then cycles of expansion and contraction make sense. The MISCONCEPTION of "creation" comes from the Stone Age ignorance that tried to supply an "answer" that would be acceptable at that time. Today we know that matter/energy can neither be created nor destroyed ergo matter/energy has always existed and will always exist in one form or another ad infinitum. The better question is why not? Why MUST there be limits to the size of the universe?
Complete nonsense! Mathematics is the language of the universe. Pi is the same value across the entire universe and it give you the exact same result on Ganymede as it does here on Earth. The logic of math establishes that the concept of infinity exists and we live in an infinite universe.
I am dubious about your statement about your big toe. Seems to me that the forces holding your big toe together overwhelm any expansion.
Sure, the concept exists but that doesn't mean there are any realized infinities. The concept of unicorns exists, but that doesn't mean there are unicorns.
[QUOTE="Derideo_Te, post: 1072369933, member: 69526" Why MUST there be limits to the size of the universe?[/QUOTE] Because infinity does not exist in nature.
The universe is not one dimentional, so there would be no end "point", per se... If you are referring to the boundaries of the universe, we quite simply do not know where those boundaries are or if the universe even HAS any...
We do not know whether or not the universe is expanding. While the observable universe is expanding, we don't know whether or not that is true of the universe as a whole. The BBT is merely one of many religious theories about a past unobserved event (in this case, describing "the expansion of the initial blob"). You always wish to treat the BBT as if it is science, but it is not. Religious conjecture... We don't know what happened back then. We don't know whether or not the universe as a whole is expanding.
The argument that math is an inherent attribute of the Universe or a human developed language construct has been ongoing for more than two thousand years and I suspect is unlikely to be resolved as one over the other. Regardless if a language invented or discovered, it is a useful tool that allows us to develop the means to model, communicate, and predict how nature seems to work within a consistent set of rules and relationships. But, math can stand within a framework independent of nature and nature works regardless of the language of math. That question is a bit ambiguous. Specifically, what do you mean by ‘End point’. It’s boundary, it’s existence, the extent of what is observed? Or....? To answer the question, we first have to define what the universe is and, despite multiple hypotheses, we have yet to reach an unambiguous description and consensus. Part of the problem is how we conceptualize it, and given our concept of it is limited by our experience of it as humans, our ability to sense it and our technological means of measurement, we still have little clue what ‘it’ is.
